What is artificial intelligence?
Over the years, many people attempted to define artificial intelligence. A lot of those definitions are summed up by Stuart Russell and Peter Norvig in their book Artificial Intelligence - A Modern Approach

The definitions of AI can be summarised as falling into the following categories:


  
  Those that address thought process and reasoning (how an AI thinks/reasons)
  Those that address behaviour (how an AI acts given what it knows)
  


Furthermore, the above 2 categories are further divided into definitions that:


  I. assess the success of an AI (to do the above) based on its ability
  to replicate human performance
  
  II. or an ability to replicate an ideal performance measure called
  'rationality' (does it do the 'right' thing based on what it knows?)


I will cite you definitions that fit into each of the above categories: 


  
  1.I. "The [automation of] activities that we associate with human thinking, activities such as decision making, problem solving, learning.." - Bellman 1978
  1.II. "The study of the computations that make it possible to perceive, reason, and act." - Winston, 1992
  2.I. "The study of how to make computers do things at which, at the moment, people do better" - Rich and Knight, 1991
  2.II. "The study of the design of intelligent agents" - Poole et al., 1998
  


In summary, AI is devoted to the creation of intelligent and rational machines that can make rational decisions and take rational actions.

I would suggest you read up on the Turing test, which Alan Turing proposed to test if a computer was intelligent. However, the Turing test has a few issues, because it is anthropomorphic.

When Aeronautical engineers created the airplane, they didn't set their goal that planes should fly exactly like birds, but rather, they started learning how lift forces were generated, based on the study of aerodynamics. Using this knowledge, they created planes.

Similarly, people in the AI world shouldn't put, IMHO, human intelligence as the standard to strive for, but, rather, we could use, say, rationality as a standard (amongst others).